Conventional server storage units include hard-drive based or similar storage devices. While hard-drives are cheap, the physical size of the hard-drives and the limitation of the storage capacity of each hard drive make it difficult to achieve high-density storage capacity in a standard 1U chassis.
Servers are typically arranged in one or more server racks. Each server rack can hold multiple pieces of rack-mountable units that are designed to fit in the server rack. Each rack-mountable unit is generally one of several standard dimensions measured in terms or a ‘rack unit.’ A rack unit, U or RU is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack. The 19-inch (48.26 cm) or 23-inch (58.42 cm) dimension refers to the width of the equipment-mounting frame in the rack, i.e., the width of the equipment that can be mounted inside the rack. One rack unit (1U) is 1.75 inches (44.45 mm) high. The size of a piece of rack-mounted equipment is frequently described as a number in “U”. For example, one rack unit is often referred to as “1U”, 2 rack units as “2U” and so on. Typical dimensions for a 1U unit are about 19 inches (W)×1.75 inches (H)×17.7 inches-21.5 inches (D).
Since the dimensions of a 1U rack-mountable chassis is fixed, depending on the physical dimensions of a hard-drive, there is only a certain memory capacity that can be packed into a traditional hard-drive based 1U storage unit. Even though hard-drives have been getting smaller in size, the inherent disadvantage of a hard-drive is its size compared to other types of memory such as Flash and DRAM.
There is a need in the industry to provide very high capacity rack-mounted storage units that can overcome the size and capacity issues of a traditional hard-drive based system.